Project Summary/Abstract Dysregulation of apoptosis pathways and loss of Human Beta Defensin-1 (hBD-1) are the common tactics adapted by cancer cells to circumvent the effects of chemotherapy. Consequently, high dose of chemotherapy is required to obtain a clinically relevant therapeutic index which in turn, compromises safety and develops resistance to therapy. The problem is acute, particularly for Fas resistant, triple negative breast cancer patients who carry poor prognosis and lack effective targeted therapies relying only on chemotherapy as the first line of treatment. Low basal apoptosis of breast, prostate and renal tumors is interconnected with downregulation of hBD-1. Lower the baseline level of apoptosis, lower the response from chemotherapy and vice versa. Similarly, higher the loss of hBD-1, higher the proliferation rate for cancer cells. Hence, reactivation of CD 95 apoptosis pathway and restoration of the lost hBD-1, specifically in tumor are the logical steps to improve the efficacy of chemotherapy. Our laboratory has designed dual targeted hBD-1 conjugated to matrix metalloproteinase-2 (MMP-2) cleavable peptides and demonstrated the anti-tumorogenic potential of hBD-1 and activation of CD 95 pathway in prostate, renal and triple negative breast cancer (TNBC) cells. Pretreatment of hBD-1 conjugate with low base level tumors is shown to be 10-25 times sensitive and synergistic with doxorubicin, carboplatin and gemcitabine for cell death induction. Hence, we propose A priori Activation of Apoptosis of Tumor Technology (AAAPT) using dual targeted hBD-1 to evoke a better clinical performance from chemotherapy, particularly for TNBC patients. Accordingly, the specific aims are; Specific Aim 1: (1) To synthesize hBD-1 conjugate and extend its anti-tumor potential from in vitro to in vivo using the SCID/nude mouse tumor model xenograft of breast cancer and (2) To optimize the therapeutic dose, the treatment time and to obtain initial pharmacokinetics of hBD-1 conjugate in order to provide information essential for Phase II studies. The endpoints include PK profiling, measuring tumor growth by bioluminescence imaging and change in endogenous markers P-glycoprotein (Pgp), thioredoxin and Bcl2. Specific Aim 2: To assess the improved efficacy of doxorubicin by hBD-1 conjugate pretreatment in Fas resistant, TNBC tumors in the SCID/nude mouse tumor model. The end point include (a) determination of tumor regression to correlate with cell death synergy with chemotherapy and (b) validate blood-borne CR-18 ELISA cell death for assessing the efficacy of AAAPT.